Field of the Invention
This invention relates to the field of electrical appliances, and in particular, it relates to a leakage current detection and protection device having a self-test function.
Description of the Related Art
Electrical appliances are widely used in households as well as industrial applications, and their safety is an important issue. Typically, leakage current protection devices are provided at electrical outlets and in plugs for electrical appliances for safety purposes. Such devices are often labeled with clearly visible signs such as “test before use” to remind the users to test the proper functioning of the leakage current protection devices. However, in practical use, due to environmental factors or installation, there is still a possibility that the leakage current protection device may malfunction during use, even if the user has tested it before use. This can be dangerous. For example, in a water heater, the electrical heating coil may become rusty or its insulating layer may be damaged due to prolonged contact with water. This may cause a leakage current which may be conducted by the water in the tank. In this situation, if the user uses water such as for a shower, electrical shock may occur, causing harm to the user.
Therefore, a leakage current detection and protection device with self-testing function is needed.